Electrical circuit testers are well known in the art, and are commonly used by electricians as well as laypersons. Such testers are also used by automotive technicians to determine the voltage at which an automotive electrical system operates. Until recent years, automotive electrical systems typically incorporated a power supply of 6-12 volts, generally through a battery. Accordingly, a 6-12 volt circuit tester was used to determine the voltage level of power supplied to these systems. This type of circuit tester had a screwdriver-type design and included a light bulb. The tester was designed so that the light bulb would become brighter as the sensed voltage increased.
Today, a demand has emerged for a higher number and sophistication of electrical vehicular features. Types of vehicular features which may require greater power are electrically heated seats, entertainment systems, navigation systems, heated windshields, preheated catalytic converters, brake-by-wire systems, electronically-controlled valves and air conditioning systems, just to name a few. Because the greater number and sophistication of features generally require a greater amount of power, a higher demand has accordingly emerged for vehicles with a larger electrical power supply.
Because this higher level of power could be supplied with increased voltage, e.g., 36-42 volts, automotive manufacturers began to consider how they could implement automotive electrical systems that supported this higher power supply. Implementation of greater power supplies has been proposed generally through one of two means. Some automobile manufacturers, such as BMW (also known as Bavarian Motor Works), have proceeded to implement a higher voltage power supply system of 36 volts. The entire electrical system of such automobiles operates at 36 volts to 42 volts or higher. However, implementation of this higher 36-42 volt system requires that all electrical components used within the system support the higher voltage.
These higher voltage systems can be expensive and relatively complex when compared to the traditional 12-14 volt systems. Greater power supplies were generally more expensive, and the manufacturer would be required to pass this cost on to the consumer. By substantially increasing the prices of its vehicles, a manufacturer risked losing customers.
Moreover, the complexity of such systems required a re-design of automotive electrical systems so that they could support these higher voltages. Delaying the introduction of a higher voltage electrical system to wait for a re-design meant delaying the introduction of a greater number and sophistication of features. The manufacturer risked losing customers because the customer demanded such features. Accordingly, in lieu of full implementation of the higher voltage systems, some automobile manufacturers have proposed a more gradual transition. This more gradual approach has been in the form of a dual voltage system that operates in both the lower 12-14 volt range as well as the 36-42 volt range.
Implementation of dual voltage systems allows the automobile manufacturers flexibility in that they need not delay the introduction of features requiring a higher power supply until such time as the electrical components or re-designs are available that support these higher power supplies. Typically, dual voltage systems require two battery systems which power different subsystems of the electrical system. Due to these dual voltage systems, an automotive technician must determine which portions of the electrical system operate in the 12-14 volt range, and which portions operate within the higher 36-42 volt range.
Determination of the appropriate voltage level is often essential to proper repair of a vehicle. Because of these dual 12-14/36-42 voltage systems, it is desirable to have a circuit tester that can inform the technician as to which voltage level an automotive electrical system operates. Moreover, because all components of a particular automobile's electrical system might operate at either a higher voltage of 36-42 volts or a lower voltage of 12-14 volts, it is desirable to know the voltage level on which the system operates.
There is a need for an automotive circuit tester and method that provide an efficient way to determine an automobile's power supply voltage, and addresses the issues associated with the emergence of higher power supply systems.